rssmith1976

I have a 92 Suburban with a 5.7ltr in it. On Friday i pulled out of my drive way and truck just shut off. The motor only has 30,000 miles on it. I got it back in my driveway and it started back up. Drove back out driveway and truck shut off again. So I replaced fuel filter and Fuel Pump Relay. Truck started right back up and ran at idle. Shut it off and it wouldnt start back up. So I replaced fuel pump. Truck started and ran at idle for about 15mins. Shut it off and it wouldnt start back up. I am able to spray starting fluid into it and it starts and but only with the fluid. Im kinda lost now. I have know idea what is making this vehicle do this but Im pretty sure its a fuel problem. Any ideas or comments would be great. Thanks

mulmur1

Have you put a fuel pressure gauge on the line to see what you are getting? Have you had a recent problem with the fuel system?

rssmith1976

Never had any problems with fuel system before. I am borrowing a fuel pressure gauge from a friend. Should have it tonight. Do you know what range it should be in?

mulmur1

Since your truck is a non vortec 350, it should be in the 10 - 13 psi range.

Sorry for the delay in responding.

rssmith1976

Not a problem at all I just appreciate the help. I will try checking it today.

shamrock246

The oil pressure switch runs the fuel pump after 4psi of oil pressure maybe that switch is going bad

rssmith1976

Ok guy let me start by thanking you for all the sugestions. Here is where Im at with the truck. I check fuel pressure and it was ok. Replaced pump to be on safe side. Also replaced fuel pump relay, fuel filter and Ignition switch that was under dash on top of steering colum. I did this because i traced one of the wires from relay to there and after taking it off I saw on of the leads inside was melted and whorn. The truck will start and run for 10 to 15 mins with no problem then just cut off as if somebody turned off the key. I was able to jump one of the wires on relay and could hear the fuel pump running also I checked the other leads on relay and they seem to be working fine. Once the truck cuts off it wont start for a while. If I let it sit for about an hour I am able to restart it. It usually will fire up on the first try. Any other advice would be great. I just dont have alot more money to poor into this thing but at the same time I need it to get back and forth to work. I just dont want to be that guy that replaces parts until it works. Not trying to be rude to anybody. Any help would be great and thank you again. Thank you

mulmur1

I hear you about replacing parts until the problem is fixed. It isn't the most cost effective solution. Hopefully we can get you closer to a solution.

Have you tested the oil pressure switch, as shamrock246 suggested. The fuel circuit that is on your truck also uses the oil pressure switch as part of the fuel system power. It is possible that the oil pressure switch is defective and is cutting off the fuel power to the fuel pump.

Please find attached an image of the fuel circuit.

It will be a challenge to reach the oil pump switch, but you should look at testing it to see if it is the problem.

You should jump the orange to the grey wire. If jump the oil pressure switch works, you should replace this switch.

Hopefully this helps.

Good luck with your repair.